In the prior art, two types of compressors were used to supercharge such an engine. One type, the positive displacement compressor, was directly connected with the engine, to be driven by the same. The other type, the centrifugal compressor, was connected to a turbine wheel, to be driven by the wheel as the wheel was driven in turn by the exhaust of the engine. Since each type was directly or indirectly driven by the engine itself, each had to operate in the engine environment, including at the temperatures generated by the engine and its exhaust. As a result, each type had to inhale air that was already heated to a temperature well above that of the general atemosphere about the engine. In fact, the centrifugal compressor delivered air that was both superheated and supercharged, because it was directly exposed to the hot exhaust of the engine. This superheated condition affected the density of the air, and therefore, its capacity to be compressed. It also affected the long term operation of the compressor itself, and particularly the bearings by which the shaft of the compressor was mounted. In fact, the bearings had to be continually bathed in oil to enable them to withstand the temperatures at which they operated, and often the oil itself had to be cooled if it was to be recirculated to the bearings. Because each type of compressor was driven off of the engine, there was also a lag in the operation of it while the engine attained sufficient speed to drive it. Moreover, the speed of the compressor itself was directly affected by that of the engine. And, of course, the compressor continued to operate only so long as the engine itself was operating. The turbine-driven compressor also had the disadvantage that the exhaust system of the engine had to be interrupted to accomodate a take-off for the turbine. Often, this in turn required that the exhaust manifold had to be offset from its normal location, so that the take-off could be accomodated directly following the engine.